Atmósfera ISSN: 0187-6236 [email protected] Universidad Nacional Autónoma de México México JAVED, WASIM; WEXLER, ANTHONY S.; MURTAZA, GHULAM; AHMAD, HAMAAD R.; BASRA, SHAHZAD M. A. Spatial, temporal and size distribution of particulate matter and its chemical constituents in Faisalabad, Pakistan Atmósfera, vol. 28, núm. 2, 2015, pp. 99-116 Universidad Nacional Autónoma de México Distrito Federal, México Available in: http://www.redalyc.org/articulo.oa?id=56536853003 How to cite Complete issue Scientific Information System More information about this article Network of Scientific Journals from Latin America, the Caribbean, Spain and Portugal Journal's homepage in redalyc.org Non-profit academic project, developed under the open access initiative Atmósfera 28(2), 99-116 (2015) Spatial, temporal and size distribution of particulate matter and its chemical constituents in Faisalabad, Pakistan WASIM JAVED Mechanical Engineering, Texas A&M University at Qatar, Doha, Qatar; Institute of Soil and Environmental Sciences, University of Agriculture, Faisalabad, Pakistan Corresponding author; e-mail: [email protected] ANTHONY S. WEXLER Air Quality Research Center, University of California-Davis, CA, USA GHULAM MURTAZA and HAMAAD R. AHMAD Institute of Soil and Environmental Sciences, University of Agriculture, Faisalabad, Pakistan SHAHZAD M. A. BASRA Department of Crop Physiology, University of Agriculture, Faisalabad-38040, Pakistan Received May 25, 2014; accepted February 6, 2015 RESUMEN Se investigaron las variaciones espaciales y temporales de aerosoles de material particulado (PM, por sus siglas en inglés) en Faisalabad, Pakistán, de junio de 2012 a abril de 2013 para conocer la distribución de componentes químicos y fracciones granulométricas en todas las estaciones del año. Se controlaron cuatro fracciones de PM (partículas totales en suspensión [TSP, por sus siglas en inglés], PM10, PM4 y PM2.5) en nueve sitios de muestreo y de manera simultánea se colectaron muestras de TSP en filtros de fibra de vidrio utilizando un dispositivo de alto volumen para toma de muestras de aire. Las muestras de TSP (144) se sometieron a un análisis químico cuantitativo para determinar la presencia de elementos traza (Pb, Cd, Ni, Zn, Cu, Fe) mediante espectroscopia de absorción atómica, así como de cationes solubles en agua (Ca2+, 2+ + + + – 2– – Mg , Na , K , NH4 ) y aniones (Cl , SO4 y NO3 ) por cromatografía iónica. Las mayores concentra- ciones de PM se observaron en sitios industriales; las concentraciones en cruces de vialidades principales fueron menores, y los valores más bajos se obtuvieron en un sitio remoto. Las concentraciones de PM fueron aproximadamente de dos a 20 veces mayores que los estándares establecidos por la Organización Mundial de la Salud y la Agencia de Protección Ambiental estadounidense. Las partículas gruesas (TSP y PM10) registraron mayores niveles durante el verano y las partículas relativamente pequeñas (PM4 y PM2.5) durante el invierno, en tanto que las concentraciones de partículas de todos los tamaños fueron menores durante la época de monzones en todos los sitios. Las concentraciones de los diferentes elementos y iones solubles en agua siguieron un patrón estacional similar al de las concentraciones de PM. Los elementos de la corteza terrestre Ca, Fe, Mg y Na fueron los mayor contribuyentes a las TSP, en tanto que las con- centraciones de origen antropogénico (Pb, Cd, Ni, Cu y Zn) fueron relativamente bajas y mostraron alta 2– variabilidad espacial. El sulfato (SO4 ) contribuyó con 50-60% de la concentración total de aniones y fue la especie predominante de éstos. Se encontró que la precipitación, la velocidad del viento y la humedad relativa fueron los factores meteorológicos que tuvieron mayor efecto sobre las concentraciones de PM. La evaluación de los datos presentados en este documento servirá como base para la modelación regional y la asignación de fuentes en el futuro. 100 W. Javed et al. ABSTRACT Spatial and temporal variations in aerosol particulate matter (PM) were investigated for distribution over the four seasons of chemical constituents and particle size fractions in Faisalabad, Pakistan from June 2012 to April 2013. At nine sampling sites, four PM mass size fractions (total suspended particulates [TSP], PM10, PM4 and PM2.5) were monitored; simultaneously, TSP mass samples were collected on glass fiber filters using a high volume air sampler. TSP samples (144) were subjected to quantitative chemical analyses for determining trace elements (Pb, Cd, Ni, Zn, Cu, Fe) using atomic absorption spectroscopy, and water-soluble 2+ 2+ + + + – 2– – cations (Ca , Mg , Na , K , NH4 ) and anions (Cl , SO4 and NO3 ) by ion chromatography. The highest PM mass concentrations were observed at industrial sites, while they were somewhat lower in major road intersections and lowest in the remote background site. It was also observed that PM mass concentrations were about two to 20 times higher than the standard limits of the World Health Organization and the US Environmental Protection Agency. Coarse particles (TSP, PM10 and PM4) were found to be highest during the summer, while relatively fine particles (PM2.5) were higher during the winter period. Concentrations of all size fractions were lowest during the monsoon sampling period at all sites. Concentrations of different elements and water-soluble ions also followed the similar temporal pattern as PM mass concentrations. The crustal elements Ca, Fe, Mg and Na were the largest contributors to TSP mass while elements of anthro- pogenic origin (Pb, Cd, Ni, Cu and Zn) had relatively lower concentrations and also showed a high spatial 2– variation. Among the anions, sulfate (SO4 ) was the predominant species contributing to 50-60% of the total anion concentration. It was found that rainfall, wind speed and relative humidity were the most important meteorological factors affecting PM concentrations. The evaluation of data presented in this paper will serve as a basis for future regional modeling and source apportionment. Keywords: TSP, PM10, PM2.5, size distribution, meteorology. 1. Introduction widely explored because it can determine the impacts Atmospheric degradation has become a severe threat on visibility, climate change and consequent health to human health and welfare in developing countries risks, as well as its potential sources and formation like Pakistan, where urbanization, motorization, and processes (Ragosta et al., 2008). Hence, the assess- industrialization coupled with concomitant growth of ment of atmospheric PM concentrations and its toxic energy use are growing rapidly. This threat is especial- constituents is a prerequisite for epidemiological ly severe in areas where technologies and strategies for studies and air quality management (Bhaskar et al., controlling emissions are limited due to lax legislative 2008; Shah et al., 2012). standards and enforcement of regulations (Colbeck et Epidemiological studies have consistently con- al., 2010; Shah and Shaheen 2010; Shah et al., 2012). firmed a strong association between ambient PM Airborne particulate matter (PM) is ubiquitous in containing toxic components and respiratory- and the atmosphere and is a major indicator of air quality cardiovascular-related increases in morbidity and in a given area. PM varies widely in size, concen- mortality, especially in urban areas (e.g., Pope 2000; tration and chemical composition. It is regulated Becker et al., 2005). This association has been re- globally under permissible standards based on size vealed to be stronger for PM2.5 than for PM10 or TSP, fractions ranging from PM2.5 (respirable fine particles, since PM2.5 can penetrate deep into the alveolar region aerodynamic diameter ≤ 2.5 µm) to PM10 (inhalable of the human lungs (Mar et al., 2004). coarse particles, aerodynamic diameter ≤ 10 µm) to The distribution and transport of PM in the atmo- TSP (total suspended particles, aerodynamic diameter sphere is markedly associated with meteorological ≤ 100 µm). PM4 (aerodynamic diameter ≤ 4 µm) is parameters such as wind speed and direction, relative also known as the respirable size fraction (Mar et al., humidity (RH), rainfall, and temperature (Pakbin et 2004). PM originates from a variety of natural (e.g., al., 2010). Therefore, PM concentrations and me- sea spray and dust storms), and anthropogenic (e.g., teorological data should be evaluated statistically power plants, brick kilns, waste incineration, industrial in order to develop correlations that can assist in emissions, motor vehicles, and agricultural activities) identifying sources and thereby assist in the design sources, as well as secondary formation processes. of cost-effective emissions control strategies. In the The chemical composition of PM has also been absence of measurements relative to other major air Characterization of atmospheric particulate matter in Faisalabad, Pakistan 101 pollutants in this part of the world, PM and its asso- in size, concentration and chemical composition in ciated chemical species can be a useful index of air the study area, Faisalabad, Pakistan, likely due to quality, providing also indirect information on the various sporadic local sources. The study was carried presence of other (primary and secondary) pollutants out to assess ambient PM concentrations and their (Ragosta et al., 2008). chemical constituents during a one-year monitoring Air pollution control in Pakistan has not yet period and then to estimate different possible sources become an